This invention relates to a Stirling refrigerator for cooling the cryoelectronic devices such as infrared detectors or the like. More particularly, it relates to a Stirling refrigerator with a freely-moving displacer.
A Stirling refrigerator of the type to which the present invention pertains has a displacer which is free to reciprocate inside a cold-finger. The cold-finger has a gas spring chamber, and one end of the displacer has a piston element formed thereon which extends into the gas spring chamber. The displacer is made to reciprocate within the cold finger by pressure variations in the cold-finger which are produced by a compressor which is connected to the cold-finger.
In a Stirling refrigerator of this type, the length of the stroke of the displacer as it reciprocates inside the cold-finger is determined by the dimensions of the cold-finger and the gas spring chamber. The displacer travels in one direction until it strikes against the end wall of the inside of the cold-finger, and then it travels in the opposite direction until the piston element which is formed on the displacer strikes against the end wall of the inside of the gas spring chamber. This repeated striking of the displacer and the piston element against the end walls of the cold-finger and the gas spring chamber produces undesirable noise and vibrations. It also produces wear of the displacer and the cold-finger, and results in a decrease in the life span of the refrigerator.